Plastic cellular lens louver having air distribution slots



March 12, 1968 J. G. HIGH 3,

PLASTIC CELLULAR LENS LOUVER HAVING AIR DISTRIBUTION SLOTS Filed Oct. 13, 1965 2 Sheets-Sheet l Qy v 55 /5 BS /5 I A rl INVENTOR LD M,

J- G. HIGH PLASTIC CELLULAR LENS LOUVER HAVING AIR March 12, 1968 2 Sheets-Sheet 2 DISTRIBUTION SLOTS Filed Oct. 13, 1965 //V VENTOR United States Patent C) 3,373,275 PLASTIC CELLULAR LENS LOWER HAVING AIR DISTRIBUTIQN SLOTS Jack G. High, Winfield, HL, assignor to MSL Industries, a corporation of Minnesota Filed st. 13, 1965, Ser. No. 495,567 10 Claims. (Cl. 240-78) ABSTRACT OF THE DISCLOSURE A one piece molded plastic lens louver of light transmitting material is disclosed with masked ventilation openings, the molded louver having a planar top Wall, a first set of parallel uniformly spaced continuous ribs integrally depending therefrom and a second set of parallel correspondingly spaced continuous ribs integrally depending from the top wall and intersecting the ribs of the first set at right angles to define a planar grid work of cells, each cell being square in plan outline and being spanned by an integral lens portion of the top wall. The louver has vertical slots opening through the top wall at uniformly distributed regions along each rib to provide a set of four air flow paths opening laterally into each cell. The slots terminate partway through each rib to be masked by the rib and preclude direct light paths.

This invention relates to light difiusers and, more particularly, is concerned with a molded plastic lens louver for effecting high emciency light transmission, and which allows through-flow ventilation while retaining effective shielding of direct light rays.

Lens louvers are commonly employed with ceiling mounted lighting banks for providing directional light transmission and more uniform light distribution. In many instances, ventilation of the light banks is desirable either by convection, or by forced flow.

The present invention provides a lens louver embodiment wherein a multiplicity of tortuous ventilation paths lead generally vertically through the louver in a fashion to be substantially masked from view from beneath. In the disclosed embodiment of a plastic lens louver, the louver is of one piece molded construction having intersecting sets of parallel continuous ribs defining a planar grid work of cells. A top wall integrally merges with all of the ribs and includes a separate lens portion for each cell and spanning the top of the cell. A plurality of slots open full height through the top wall and extend partway into the ribs at the regions that flank the cells, so that each of these slots constitutes a generally vertical portion of an air circulation flow path and is masked by the unbroken portion of the rib.

Other features and advantages of the invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which show structure embodying preferred features of the present invention and the principles thereof, and What is now considered to be the best mode in which to apply these principles.

In the accompanying drawings forming a part of the specification, and in which like numerals are employed to designate like parts throughout the same:

FIGURE 1 is a diagrammatic view illustrating the louver of this invention in association with conventional light sources;

FIGURES 2 and 3, respectively, are fragmentary top and bottom plan views, greatly enlarged, and further illustrating the louver structure of this invention;

FIGURE 4 is a fragmentary elevational view of the louver;

FIGURE 5' is an enlarged fragmentary cross-sectional ice view taken approximately as indicated on the line 55 of FIG. 2, the line being staggered to illustrate various features of the structure; and

FIGURE 6 is a similar sectional view taken at right angles to that of FIGURE 5, as indicated by the line 6-6 on FIGURE 2.

Referring now to the drawings, the plastic lens louver is designated generally at 10 in the diagrammatic view of FIGURE 1 and is shown positioned in the illumination field from a lighting bank comprised of a number of light sources 11. The light sources 11 normally are located in a recessed mounting chamber provided in a ceiling area, and usually are fluorescent tubes, though incandescent lamps are sometimes employed. Normally, the louver 10 spans the bottom opening of the mounting chamber it being carried in a peripheral frame (not shown) of the usual type provided in such installations. The illumination as transmitted by the louver is to be diffused and dispersed substantially uniformly. It is also important that the louver exhibit a high etficiency of light transmission through it.

It is frequently desirable in lens louver installations to provide improved ventilation of the plenum or mounting chamber and the plastic lens louver 10 has a unique structure affording adequate air circulation paths that are tortuous and lead generally vertically through the body of the louver without allowing direct transmission of light.

The plastic lens louver 10 as disclosed herein is a one piece molded body of a light transmitting material such as a clear transparent plastic, for example, either an acrylic resin such as Du Ponts Lucite or a styrene is suitable.

The one piece louver body is comprised of a set of parallel continuous ribs 12 and a set of parallel continuous ribs 13, the sets of ribs 12 and 13 being coplanar and intersecting to define a planar grid work of cells 14. Each of the cells 14 is of quadrangular plan outline configuration and is bordered on each of its four sides by a portion of a corresponding rib. The louver body has lens wall structure 15 spanning each cell at the top and integrally merging with each rib portion bordering the particular cell. In the embodiment illustrated herein each lens structure 15 is of diamond shape configuration, has a flat top face 1ST and a concave or recessed underface 15C so that the depth of the lens wall is a maximum at the region where it joins the bordering rib portion. The lens walls 15 and ribs 12, 13 are coplanar at their upper extremities to present a fiat substantially smooth top face for the louver.

It is apparent from the drawings that the sets of parallel ribs 12, 13 in the illustrated louver embodiment intersect at right angles to define cells 14 that are rectangular in plan outline or more specifically are square as the rib spacings are identical in each rib set.

To provide requisite ventilation each n'b has vertical slots 128, 138 opening through the top face of the louver in regularly spaced relationship and in a pattern wherein each rib has one slot corresponding to each row of cells 14 through which the rib extends. Thus, each cell is bordered on four sides by a pair of slots 12S and a pair of slots 138, each slot providing a tortuous generally vertical air circulation fiow path. Each slot is deep enough to extend below the lowest extremity of the lens wall 15 and provide separate laterally opening flow regions leading into each of the two cells that are bordered by the slot. The unbroken portion of rib 12U, 13U which underlies the lower end of each slot serves to mask the slot in a fashion to prevent an observer located beneath the louver from directly viewing the open slot. Thus, the slot arrangement shields direct light rays from the light sources 11 from the eyeof anobserver locatedtherebeneath. Each of the ribs 12- and 13 and each of the slots 12S and 135 is uniformly tapered in Width in a downward direction, the relationship being such that each slot is of maximum width at the top, spans the full width of the corresponding rib portion, and terminates partway through the rib. The uniform taper of the ribs and slots facilitates mold release of the louver and enables adequate air circulation while masking direct light rays.

In the particular embodiment illustrated herein, the ribs 12 are spaced about 0.72 inch on centers as are the ribs 13 and each rib is about inch wide at the base, and terminates about /2 inch from the top face. Each of the slots is about A inch deep and about 0.22 inch wide at the top face. The ribs and slots both have a uniform downward taper of about 9 from vertical as measured along each slot or rib side face.

As is apparent in FIGURES 4, and 6, the regular spacing of the .slots and the transverse alignment of the slots providestransverse through passages at various regularlyspaced locations through the louver. For example, the louver ends of the slots 12S and central regions of the intervening cells 14 constitute a set of lateral passages 16, (FIG. 5). correspondingly, the lower ends of the slots 13S and central regions of the intervening cells. constitute a set of lateral passages 17 (FIG. 6) that intersect the passages16. These lateral passages 16 and 17 enable widespread distribution and more uniform air circulation flow through the louver.

Thus, while. preferred constructional features of the invention are embodied in the structure illustrated herein, it is to be understood that changes and variations may be made. by those skilled in the art without departing from the spirit and scope of the appended claims.

What is claimed is:

1.. A one piece molded plastic lens louver of light transmitting material having intersecting sets of parallel continuous, ribs defining a planar grid workof cells each of quadrangular plan outline configuration and bordered on. each of its four sides by a portion of a corresponding rib, there being a single rib portion intermediate any pair of adjacent cells each cell having lens wall structure spanning the. same and integrally merging with each rib portion borderingv the. same, said louver having at each such rib portion a vertical slot that is open at the top, that spans the width of such rib. portion, and that ends partway through the rib portion at a lower elevation than the lens wall structure to define at each cell a set of four tortuous, generally vertical air circulation flow paths each masked by the lower region of the corresponding rib portion. a

2. A louver in accordance with claim 1 and wherein each rib and each slot tapers in a downwarddirection.

3. A one piece molded plastic lens louver of light transmitting material having first and second sets each comprised. of parallel continuous ribs, said sets of ribs intersecting at right angles to define a planar grid work of cells. each of rectangular plan outline configuration and bordered on each of its four sides by: a portion of a corresponding rib, there being a single rib portion intermediate any pair of. adjacent cells, each cell having lens wall structure spanning the same and integrally merging with each rib portion bordering the same, said louver having at each rib portion a vertical slot that is open at the top, that spans the width of. such rib portion, and that ends partway through the rib portion at a lower elevationv than the lens wall structure to define at each cell a set of four tor- 4 tuous, generally vertical air circulation flow paths each masked by the lower region of the corresponding rib portion.

4. A louver in accordance with claim 3 and wherein the ribs of each set are spaced a uniform equal distance and are of substantially uniformly tapered width in a downward direction.

5. In a one piece molded plastic lens louver of light transmitting material and having a substantially planar top wall, a first set of mutually parallel continuous ribs underlying and integrally depending from said top wall, and a second set of mutually parallel continuous ribs underlying and integrally depending from said top wall and intersecting the ribs of the first set to define a planar grid work of cells, each of quadrangular plan outline configuration and spanned by a lens section of the top wall there being a single rib intermediate any pair of adjacent cells, said louver having a plurality of spaced vertical slots opening through the top wall at regions along each rib to provide at least one tortuous, generally vertical air circulation fiow path leading vertically through each cell, each said slot being of maximum size at the top, spanning the width of the corresponding rib and ending partway through'such corresponding rib at a lower elevation than any adjacent lens section and with the slot substantially masked by the corresponding rib.

6. An arrangement in accordance with claim 5 and wherein each rib and each slot has a substantially uniform downward taper.

7. In a one piece molded plastic lens louver of light transmitting material and having a substantially planar top wall, a first set of mutually parallel uniformly spaced continuous ribs underlying and integrally depending from said top wall, and a second set of mutually parallel correspondingly uniformly spaced continuous ribs underlying and integrally depending from said top wall and intersecting the ribs of the first set at right angles to define a planar grid work of cells, each square in plan outline configuration and spanned by an integral lens section of the top wall, there being a single rib intermediate any pair of adjacent cells, said louver having a plurality of vertical slots opening through the topwall at uniformly distributed regions along each rib to provide a set of four vertical air circulation flow paths leading vertically through each cell, each said slot being of maximum size at the top, spanning the width of the corresponding rib and ending partway through such corresponding rib at a lower elevation than any adjacent lens section and with the slot substantially masked by the corresponding rib.

8. An arrangement in accordance with claim 7 and wherein each rib and each slot has a substantially uniform downward taper.

9. A louver in accordance with claim 1 and wherein each slot is substantially as deep as it iswide and hasa top region opening through a horizontal planar rib face.

10. A louver in accordance with claim 1 and wherein each rib is about /3 as wide as the cell adjacent thereto.

References Cited UNITED STATES PATENTS 1,913,249 6/1933 Sersen 98-40 2,859,334 11/1958 Guth 2409 3,129,895 -4/ 1964 Franck 240-78 NORTON ANSI-1BR, Primary Examiner.

M. H. HAYES, Assistant Examiner. 

